Chen Ying-Chung, Shih Wei-Che, Chang Wei-Tsai, Yang Chun-Hung, Kao Kuo-Sheng, Cheng Chien-Chuan
Department of Electrical Engineering, National Sun Yat-Sen University, Kaohsiung, 80424 Taiwan.
Department of Computer and Communication, Shu-Te University, Kaohsiung, 82445 Taiwan.
Nanoscale Res Lett. 2015 Feb 18;10:69. doi: 10.1186/s11671-015-0736-3. eCollection 2015.
Film bulk acoustic resonators (FBARs) have been evaluated for use as biosensors because of their high sensitivity and small size. This study fabricated a novel human IgE biosensor using shear-mode FBAR devices with c-axis 23°-tilted AlN thin films. Off-axis radio frequency (RF) magnetron sputtering method was used for deposition of c-axis 23°-tilted AlN thin films. The deposition parameters were adopted as working pressure of 5 mTorr, substrate temperature of 300°C, sputtering power of 250 W, and 50 mm distance between off-axis and on-axis. The characteristics of the AlN thin films were investigated by X-ray diffraction and scanning electron microscopy. The frequency response was measured with an HP8720 network analyzer with a CASCADE probe station. The X-ray diffraction revealed (002) preferred wurtzite structure, and the cross-sectional image showed columnar structure with 23°-tilted AlN thin films. In the biosensor, an Au/Cr layer in the FBAR backside cavity was used as the detection layer and the Au surface was modified using self-assembly monolayers (SAMs) method. Then, the antigen and antibody were coated on biosensor through their high specificity property. Finally, the shear-mode FBAR device with k t (2) of 3.18% was obtained, and the average sensitivity for human IgE detection of about 1.425 × 10(5) cm(2)/g was achieved.
薄膜体声波谐振器（FBAR）因其高灵敏度和小尺寸而被评估用作生物传感器。本研究使用具有c轴23°倾斜AlN薄膜的剪切模式FBAR器件制造了一种新型的人IgE生物传感器。采用离轴射频（RF）磁控溅射法沉积c轴23°倾斜的AlN薄膜。沉积参数采用工作压力5 mTorr、衬底温度300°C、溅射功率250 W以及离轴与轴上距离50 mm。通过X射线衍射和扫描电子显微镜研究了AlN薄膜的特性。使用带有CASCADE探针台的HP8720网络分析仪测量频率响应。X射线衍射显示出（002）择优纤锌矿结构，横截面图像显示出具有23°倾斜AlN薄膜的柱状结构。在生物传感器中，FBAR背面腔中的Au/Cr层用作检测层，并且使用自组装单分子层（SAMs）方法对Au表面进行修饰。然后，通过抗原和抗体的高特异性将它们涂覆在生物传感器上。最后，获得了kt（2）为3.18%的剪切模式FBAR器件，并且实现了对人IgE检测的平均灵敏度约为1.425×10（5）cm（2）/g。
